Automator actions assembled into a workflow can be used by System Imaging Utility to create custom images.
System Image Utility harnesses the power of Automator to help you create custom images by assembling workflows. The basic building block of a workflow is an automator action. You define the image customization by assembling automator actions into a workflow.
Instead of being a do-it-all tool, an action is designed to perform a single task well, such as customizing a software package or adding a user account. By combining several actions into a workflow, you can quickly accomplish a specific task that no one action can accomplish on its own.
You use workflows to create customized NetInstall or NetBoot images, depending on the goals of your task:
Workflows that create custom NetInstall images assemble an image that installs OS X onto the computer, either originating from installation volumes or from an installed OS X volume. This image boots into the installer environment or similar shell environment and performs the workflow steps you define.
Workflows that create custom NetBoot images assemble a bootable image from installation volumes or from an installed OS volume. This image can be directly installed onto a target volume using the asr command-line tool or NetBoot.
For more information, see Assemble workflows.